Rod ends in single shear

Folks:

First let me say that I know well that everything is supposed to be in
double shear. Lord knows I have busted my butt to make sure
everything is in double shear.

But.

I have a portion of my aileron circuit that has a fork fitting to
provide the requisite double shear. However the bolt hole in the
crank is seeing some misalignment and is starting to wallow the hole.
I really, really should replace the fork fitting with a rod end (i.e.
it never should have been a fork fitting to begin with, it was a spur-
of-the-moment fix that was really just a band-aid). But the crank
being driven by the fork is going to be impossible to replace with a
two-armed crank that can nest a rod end.

So, I am faced with the possibility of using a rod end in single
shear. I know that this is viewed as being undesirable, as the
bearing can be popped out of the eye under certain conditions. I also
know that the traditional trick to compensate for this is to use a 970
washer (large area washer) on the outer end of the bolt holding the
rod end, such that if the bearing leaves the eye the washer prevents
the rod from departing the scene.

Now, with all of that said, here's my question: How bad is it really
to have the rod end in single shear if I do the washer trick? It's an
aileron rod, I do not think it sees much load at all--certainly far,
far short of it's rated load. I have seen several planes out there
with rod ends in single shear, so it can't be complete suicide . . .
right? No?

Thank you for your thoughts.

Steve.

On Tue, 25 Sep 2007 21:58:46 -0700, "Steve S."
wrote:

Folks:

First let me say that I know well that everything is supposed to be in
double shear. Lord knows I have busted my butt to make sure
everything is in double shear.

But.

I have a portion of my aileron circuit that has a fork fitting to
provide the requisite double shear. However the bolt hole in the
crank is seeing some misalignment and is starting to wallow the hole.
I really, really should replace the fork fitting with a rod end (i.e.
it never should have been a fork fitting to begin with, it was a spur-
of-the-moment fix that was really just a band-aid). But the crank
being driven by the fork is going to be impossible to replace with a
two-armed crank that can nest a rod end.

Now, with all of that said, here's my question: How bad is it really
to have the rod end in single shear if I do the washer trick? It's an
aileron rod, I do not think it sees much load at all--certainly far,
far short of it's rated load. I have seen several planes out there
with rod ends in single shear, so it can't be complete suicide . . .
right? No?

Thank you for your thoughts.

I have a number of them that have been in service for over 20 years,
all with the large washer. Works for me.

Ed Sullivan, Jungster II

Ed Sullivan wrote:
On Tue, 25 Sep 2007 21:58:46 -0700, "Steve S."
wrote:


Folks:

First let me say that I know well that everything is supposed to be in
double shear. Lord knows I have busted my butt to make sure
everything is in double shear.

But.

I have a portion of my aileron circuit that has a fork fitting to
provide the requisite double shear. However the bolt hole in the
crank is seeing some misalignment and is starting to wallow the hole.
I really, really should replace the fork fitting with a rod end (i.e.
it never should have been a fork fitting to begin with, it was a spur-
of-the-moment fix that was really just a band-aid). But the crank
being driven by the fork is going to be impossible to replace with a
two-armed crank that can nest a rod end.


Now, with all of that said, here's my question: How bad is it really
to have the rod end in single shear if I do the washer trick? It's an
aileron rod, I do not think it sees much load at all--certainly far,
far short of it's rated load. I have seen several planes out there
with rod ends in single shear, so it can't be complete suicide . . .
right? No?

Thank you for your thoughts.


I have a number of them that have been in service for over 20 years,
all with the large washer. Works for me.

Ed Sullivan, Jungster II

Long as teh arm and bolt are stiff enough not to deform - who cares...

On Sep 26, 12:34 am, cavelamb himself wrote:
Ed Sullivan wrote:
On Tue, 25 Sep 2007 21:58:46 -0700, "Steve S."
wrote:

Folks:

First let me say that I know well that everything is supposed to be in
double shear. Lord knows I have busted my butt to make sure
everything is in double shear.

But.

I have a portion of my aileron circuit that has a fork fitting to
provide the requisite double shear. However the bolt hole in the
crank is seeing some misalignment and is starting to wallow the hole.
I really, really should replace the fork fitting with a rod end (i.e.
it never should have been a fork fitting to begin with, it was a spur-
of-the-moment fix that was really just a band-aid). But the crank
being driven by the fork is going to be impossible to replace with a
two-armed crank that can nest a rod end.

Now, with all of that said, here's my question: How bad is it really
to have the rod end in single shear if I do the washer trick? It's an
aileron rod, I do not think it sees much load at all--certainly far,
far short of it's rated load. I have seen several planes out there
with rod ends in single shear, so it can't be complete suicide . . .
right? No?

Thank you for your thoughts.

I have a number of them that have been in service for over 20 years,
all with the large washer. Works for me.

Ed Sullivan, Jungster II

Long as teh arm and bolt are stiff enough not to deform - who cares...

The single arm may not have the resistance to twisting that
the two arms do together. You'd want to compare single-arm setups with
what you have. An arm that allows twisting will eventually fail or
might allow enough aileron play to start flutter. Both are bad news.

Dan

On Wed, 26 Sep 2007 20:33:05 -0700, wrote:


aileron rod, I do not think it sees much load at all--certainly far,
far short of it's rated load. I have seen several planes out there
with rod ends in single shear, so it can't be complete suicide . . .
right? No?

Thank you for your thoughts.

I have a number of them that have been in service for over 20 years,
all with the large washer. Works for me.

Ed Sullivan, Jungster II

Long as teh arm and bolt are stiff enough not to deform - who cares...

The single arm may not have the resistance to twisting that
the two arms do together. You'd want to compare single-arm setups with
what you have. An arm that allows twisting will eventually fail or
might allow enough aileron play to start flutter. Both are bad news.

Dan

As long as the uiball is tight against the bell crank or horn there
will be no play.

:Ed

Ed Sullivan wrote:
On Wed, 26 Sep 2007 20:33:05 -0700, wrote:



aileron rod, I do not think it sees much load at all--certainly far,
far short of it's rated load. I have seen several planes out there
with rod ends in single shear, so it can't be complete suicide . . .
right? No?

Thank you for your thoughts.

I have a number of them that have been in service for over 20 years,
all with the large washer. Works for me.

Ed Sullivan, Jungster II

Long as teh arm and bolt are stiff enough not to deform - who cares...

The single arm may not have the resistance to twisting that
the two arms do together. You'd want to compare single-arm setups with
what you have. An arm that allows twisting will eventually fail or
might allow enough aileron play to start flutter. Both are bad news.

Dan


As long as the uiball is tight against the bell crank or horn there
will be no play.

:Ed

True, nut not necessarily the whole story, Ed.

Because there is a small moment due to the off-axis pushrod, the
arm itself could flex.

If the arm is really thin metal (as possible if a sheet steel part
were used) it MIGHT be possible to excite the aileron system -
ie: cause flutter.

Richard

On Thu, 27 Sep 2007 01:45:50 -0500, cavelamb himself
wrote:


As long as the uiball is tight against the bell crank or horn there
will be no play.

:Ed

True, nut not necessarily the whole story, Ed.

Because there is a small moment due to the off-axis pushrod, the
arm itself could flex.

If the arm is really thin metal (as possible if a sheet steel part
were used) it MIGHT be possible to excite the aileron system -
ie: cause flutter.

Richard


That could be true, however I only attached rod end bearings to 4130
tubing.

Ed

Ed Sullivan wrote:
On Thu, 27 Sep 2007 01:45:50 -0500, cavelamb himself
wrote:



As long as the uiball is tight against the bell crank or horn there
will be no play.

:Ed

True, nut not necessarily the whole story, Ed.

Because there is a small moment due to the off-axis pushrod, the
arm itself could flex.

If the arm is really thin metal (as possible if a sheet steel part
were used) it MIGHT be possible to excite the aileron system -
ie: cause flutter.

Richard



That could be true, however I only attached rod end bearings to 4130
tubing.

Ed


One end, maybe.

But tube arms???

On Thu, 27 Sep 2007 14:12:43 -0500, cavelamb himself
wrote:



That could be true, however I only attached rod end bearings to 4130
tubing.

Ed


One end, maybe.

But tube arms???

I'm really not sure I understand where you're coming from, but by arms
if you are referring to bellcranks or horns, I would certainly not
skimp on thickness.

On Thu, 27 Sep 2007 21:18:38 -0400, Ernest Christley
wrote:




The horns on the Dyke Delta are .100 4130. The prototype had flown for
over 40 years. If the horn was thin enough to deform from the rod end
being in single shear, it will bend just as much in double shear. There
is room for twist in the rod end even with both sides captured.

That may be so, but it has not been my experience. My horns and bell
cranks are a bit heavier however.

Anyway I'm too old to care

Ed